case study p2: vertical integral thrust bearing upgrade
TRANSCRIPT
Landon Cooper
Pump Background Problem Solution Calculations Benefits Lesson learned Current status
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Produced Water 2 pump in series Pump 1◦ Suction: 220 PSIG◦ Discharge: 1720 PSIG
Pump 2◦ Suction: 1720 PSIG◦ Discharge: 3320 PSIG
Temp 130°F
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Pump originally designed and installed by a reputable OEM.
Pump had been repaired and upgraded several times by various repair shops.
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Cast Iron bronze construction 20 + pumps at site Each pump had various
upgrades and design changes. Such as the bearing bushing in the housing.
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Upgraded pump shown
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Customer wanted to do a complete overhaul on a set of pumps.
This included◦ HVOF wear parts◦ Duplex material◦ Mechanical seal.
Material and flush plan.◦ Integral thrust bearing
(discussed later)
The end user was going to purchase a new motor for these pumps. Due to the thrust load the motor was expensive and had a long lead time. The end user wanted an alterative solution.
Customer wanted options when upgrading other pumps in the field.
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The engineering team offered a vertical thrust bearing as a possible solution.
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Calculate Pump down thrust.◦ Thrust and speed determine bearing thrust pot
Select a Bearing to fit housing foot print. Verify Bearing life will meet requirements Verify 2nd pump in series can handle up-thrust from
first pump during start up.
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= Force on sleeve
=Rotor Weight
= Hydraulic force
= Force on shaft end10
)(*4
221 bb DDA
Net Pump assembly axial thrust:
Unbalanced area:
Thrust factor:
- Net Bowl hydraulic thrust:∗ ∗ ∗
2.31 ∗ ∗
= Rotor weight= Force shaft sleeve
= Force on end of shaft
C= experimental thrust coefficient
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Pump 1 @ Design
Pump 2 @ Design
Pump 1 @ Min. Flow
Pump 2 @ Min. Flow
FH +6060 +6060 +8333 +8333Wr +305 +305 +305 +305Fslv -6 -48 -6 -64Fs -447 -3379 -447 -4478Fn (Total) 5912 lbf 2938 lbf 8184 lbf 4095 lbf
+ Down direction- Up direction
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Up thrust on Second PumpF(static) -3495 lbfF(start) -5313 lbf
30%*
The radial bearing is used to take the momentary up-thrust during and before start-up. The bearing selected is a radial deep groove bearing with a static load rating of 14400 lbf. According to the bearing manufacture the allowable axial load is 0.5*14400 lbf.
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Where: C = 165000 lbf - bearing load rating n = 3560 rpm
310
110 )93.
(60
1000000
dskfmhD P
Cn
aaL
Pump 1 Pump 2
P @ Design 5912 lbf 2938 lbfP@ Min Flow 8184 lbf 4095 lbfL10 @ Design 308,794 hr 3,176,403 hrL10 @ Min Flow 132,996 hr 1,337,127 hr
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Spherical Roller Thrust bearing
Radial Deep Groove Bearing
Fan Shroud
Shaft Sleeve/ oil carrier
Spring
Cooling tube
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New shaft Design New Coupling Modifications to the Head and Motor Stand.
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Lowers motor cost. Easier bearing
maintenance.◦ Can leave pump motor in
place.
• Bearing housing has to be removed to service Mechanical seal.
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Allow more room for design changes to accommodate a more maintenance friendly Discharge head. – Mechanics would of like more room for installing the Mechanical seal
The large start-up up-thrust was limited by the radial bearing.
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Pumps are running.
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